Ensuring correct sample preparation for a COVID-19 test
I’m sure that I’m not the only parent with a negative experience of trying to shove a long stick towards the back of my child’s throat or up their nose for the first time. If you had told me that I would be doing it twice a week and my kids would tolerate it, I would never have believed you. My children prefer taking a nose sample rather than a throat one, but their ability to grin and bear it, especially if there is a good reason (“we can only go to see granny if you do this!”), has been surprising.
Self-testing kids might not be as big a problem as we once thought.
But are we getting ‘enough’ of the good stuff? How far up is far enough for a nose swab?
Well, for self-testing, this is where we are likely to make the most errors, along with the next two steps of mixing the sample with the solution in the extraction buffer tube and placing droplets on the strip. I didn’t even realise there was a potential for ‘over mixing’ a solution (excessive shearing forces breaking down the virus), or that putting an extra drop for good measure might cause ‘flooding’ and obscure the result and accuracy of tests.
These misuses may not apply to this specific test, but we need to be clear on the requirements, particularly if we are switching between test kits from different providers. For instance, one provider of LFTs stipulated that two drops were required, whereas another one mentioned four were needed.